1. Technology Field
The present invention generally relates to intravascular catheters. In particular, the present invention relates to a dual lumen guidewire support catheter that facilitates the accurate positioning and delivery of a guidewire for passing through a chronic total occlusion (“CTO”) of a body vessel.
2. The Related Technology
A CTO is a severe narrowing of a blood vessel, such as a coronary vessel, that results in a complete or nearly complete occlusion of the primary vessel. CTOs are quite common in diseased coronary vessels and typically occur where plaque is formed in the vessel, gradually reducing the size of the lumen in the vessel until it becomes quite small and results in thrombus formation resulting in a stenosis forming a total occlusion. As the total occlusion becomes chronic, the stenosis or blockage generally has a tendency to continue to grow with fibrous end caps being formed at the proximal and distal ends of the occlusion. These fibrous end caps tend to be fairly tough but do have varying degrees of toughness.
Angioplasty and stent implantation procedures are commonly employed to treat CTOs or other stenoses that form within the vascular anatomy of a patient. During an angioplasty, or percutaneous transluminal coronary angioplasty (“PTCA”) procedure, a guiding catheter is advanced through the vasculature of the patient to a desired point. A guidewire, positioned within a balloon catheter, is extended from a distal end of the guiding catheter into the patient's coronary artery until it penetrates and crosses a blockage to be dilated. The balloon catheter is then advanced through the guiding catheter and over the previously introduced guidewire, until it is properly positioned across the blockage. Once properly positioned, the balloon is inflated to a predetermined size such that the material causing the blockage is compressed against the arterial wall, thereby expanding the passageway of the artery. The balloon is subsequently deflated, blood flow resumes through the dilated artery, and the balloon catheter is removed.
In attempting to treat such chronic occlusions, there is a need to have guidewires which can extend through the stenoses forming the chronic occlusions so that various types of treatments can be performed. Heretofore attempts to place guidewires across such stenoses or blockages have resulted in the guidewires following fissures in the plaque and creating false lumens or with the guidewire being directed in such a manner so as to perforate the wall of the vessel causing a vessel dissection. In attempting to perform such a guidewire crossing, it often has been necessary to exchange the guidewire for a stiffer wire, which is time consuming.
One of the methods used in crossing a CTO is the parallel wire technique. The parallel wire technique uses a first wire to try and cross the CTO. Often, the first guidewire passes into a dissection plane, sub-intimal plane or likewise tracks out of the vessel true lumen, the physician leaves the initial guidewire in place and uses it as a reference point to assist in passing a second wire through the CTO and into the other side of the vessel true lumen. However, when the second guidewire is inserted within the lumen, it is likely that the second guidewire will follow the same path already forged by the first guidewire. It is very difficult to get back on to the proper track necessary for a crossing of the CTO once the second guidewire has passed into a dissection plane or other false lumen.
In light of the above discussion, a need exists in the art for a catheter capable of use with multiple guidewires employed in treating intravascular blockages. In particular, a catheter configuration is needed that alleviates problems occasioned by the advancement of the catheter along a first guidewire that has been directed outside of the vessel lumen. Any solution to the above need should increase the likelihood of a successful crossing of an intravascular blockage. Moreover, any proposed solution should be adaptable for use with a variety of catheter types and configurations.